Computing systems may include devices such as a printed circuit board (PCB) having input/output bus connections. As input/output (I/O) speeds increase, channel loss, such as return loss and insertion loss associated with impedance discontinuities become a bottle-neck of the bus performance. In some scenarios, impedance discontinuities occur due to traces connecting to via stubs. A via stub is a portion of a via wherein the portion is not a main propagation path, or is not an intended propagation path. While the via may be designed to propagate a signal, connections between a via and other components, such as a trace, may leave a stub of the via that may cause a reflection of the propagating signal. Via discontinuities may arise from reflections of a signal due to the unused portion of the long via stub.
The same numbers are used throughout the disclosure and the figures to reference like components and features. Numbers in the 100 series refer to features originally found in FIG. 1; numbers in the 200 series refer to features originally found in FIG. 2; and so on.